1.05.2011

Much of a cyclist's effort is to push aside the air in front of him. Riding in the slipstream of another rider is easier than taking the lead. The difference increases with speed. Racers have known this from the start and have ridden accordingly, often sharing the lead between them. From there it is a small step to employing a rider to create a slipstream while his leader rides behind him.

It is team tactics which so often win or lose races - and the lieutenants and the dog soldiers who expend their energy blocking chasing moves when they have riders up the road in a position to win. It is they who ride out into the wind so their aces can get an easier ride tucked inside their wheel [close to the rider in front and in his shelter]. Rare indeed is the major victory that cannot be credited in large part to the groundwork laid by the domestiques.[1]

Posted from WIKI

If you're out on a casual ride with bud's and your not taking a turn in the lead.. you become something entirely different. You become a wheelsucker.